1. Field of the Invention
This invention relates to a method for producing by silicon nitride layer on a substrate by a chemical vapor deposition (CVD) process making use of a thermochemical reaction (low pressure chemical vapor deposition) and a photochemical reaction.
More particularly, this invention relates to a technology for producing a stabilized layer of semiconductor devices, gate insulated layer of IG-FET and insulated layer for capacitors etc.
2. Description of the Prior Art
Conventionally, a silicon nitride layer is produced in such a manner that silane (SiH.sub.4) and ammonia (NH.sub.3) are reacted by a plasma chemical vapor deposition utilizing a glow discharging to prepare the layer on a substrate of about 200.degree. to 400.degree. C.
Thus formed silicon nitride layer has odd electric charges due to the presence of unpaired couplings of silicon, silicon clusters, OH group etc. left in the matrix. Because of the presence of the electric charge, the silicon nitride could not be applied as a final coating for MOS, IC and so on.
Therefore, in the field of producing a semiconductor device (in particular, EP-ROM), there has been a strong demand for producing a silicon nitride layer in which silicon atoms are hardly clustered.